A. Hypotheses Studies, primarily in white populations, have demonstrated that only 50-70% of premature coronary heart disease (CHD) is accounted for by known traditional risk factors (hypertension, dyslipidemias, and smoking). Several newly identified "nontraditional" risk factors appear promising in explaining a greater portion of CHD. We have shown that occult disease can be identified in asymptomatic apparently healthy siblings of persons with CHD prior to 60 years of age. Certain risk profiles discriminate those with and without occult disease. Further, occult disease at baseline has predicted subsequent CHD events. Virtually no family studies have included a sufficient sample of African Americans. Our hypotheses are proposed for the 480 African American brothers and sisters of persons with premature CHD being accrued in a new National Heart Lung and Blood (NHLBI) Intervention Study commencing April 1, 1998. Hypothesis 1: Traditional risk factors (hypertension, hypercholesterolemia, low HDL cholesterol, obesity (BMI >27), current smoking, increased left ventricular mass and glucose will be significantly associated with occult coronary ischemia . Hypothesis 2: Nontraditional risk factors elevated levels of serum insulin, fibrinogen, apolipoprotein B, homocysteine, and Lp(a)) will be significantly associated with occult coronary ischemia. Hypothesis 3: There will be a significant relationship between abnormal carotid wall intimal thickness and /or carotid plaque and the presence of occult coronary ischemia.